Trey is a White Deer who appears in the books and the TV series. He becomes leader of the white deer herd shortly after The Great Stag's death. Unlike his predecessor, Trey is a disrespectful, arrogant, and narcissistic stag, and is not friendly with the Farthing Wood animals as he believes that White Deer Park should be reserved for white deer only. Trey is injured by a fallen tree during the great storm and, although the other stags free him under instruction from Fox, he is dethroned as leader of the herd and not seen again. In the TV series only Laird helps to free him and he is cared for by The Warden before returning to the park, now free of his temper because of the extra space created by the expansion of the reserve.

After the death of the Great Stag, Trey makes it very clear to the other animals that he does not welcome their presence in White Deer Park and orders them not to drink from the pond and to stay away from the juciest stalks of grass as they are reserved for the white deer herd. Trey tries to terrorize the Farthing Wood animals, first chasing Leveret away when he is resting in the sun, then butting Badger into the pond when he takes a drink. In this instance Plucky intervenes and bites Trey on the leg to keep him away from Badger, then Badger bites Trey again to allow them both to escape to the safety of a disused set. Trey waits outside for them to come out, but Plucky returns and tells him that the other stags are becoming friendly with the hinds, so he quickly heads off to stop them.

When the time of the rut comes, Trey easily wins and becomes leader of the white deer herd. At this point he believes that he has complete control over every other animal in the park. He establishes his rule over the other stags in the herd and does not allow them to come near the hinds. When he leads the hinds to drink at the pond Trey keeps watch and chases away any other creature that tries to drink there. However, when the Farthing Wood animals all drink together among the hinds he cannot do anything to get rid of them and he is forced to lead the hinds away when the hurricane arrives.

Once the storm is over, Trey tries to chase the other stags out of the park through a gap that has appeared in the fence, but he pushes one of them into a swaying pine tree which falls and lands on Trey, pinning him to the ground. Fox and Vixen arrive and Trey tells them to leave him in peace, but Fox instructs the other stags to use their antlers to lift the tree and set Trey free. Shortly afterwards, The Warden arrives and takes Trey away, and he is never seen again by any of the Farthing Wood animals.

His role and attitude in the TV series is similar with a few key differences. He is the main reason that Weasel's family leaves the park after he attacks upon discovering that she is pregnant. He knocks Shadow into the pond instead of Badger and is never bitten, but consistently outwitted by Plucky. He also threatens to kill Dash when she causes a stampede in the herd in order to save Toad from a large group of rats.

After being injured during the hurricane, Laird is the only stag to save him before he is taken away by The Warden.

Trey appears briefly at the end to explain that the new reserve has been merged with the rest of White Deer Park. The increased space seems to have cured him of his temper and arrogance, though he is still prejudiced against Weasels.